EP0352308B1 - Method of sputtering - Google Patents

Method of sputtering Download PDF

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Publication number
EP0352308B1
EP0352308B1 EP89900684A EP89900684A EP0352308B1 EP 0352308 B1 EP0352308 B1 EP 0352308B1 EP 89900684 A EP89900684 A EP 89900684A EP 89900684 A EP89900684 A EP 89900684A EP 0352308 B1 EP0352308 B1 EP 0352308B1
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EP
European Patent Office
Prior art keywords
target
spherical
plasma
substrate
substrates
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP89900684A
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German (de)
English (en)
French (fr)
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EP0352308A1 (en
EP0352308A4 (en
Inventor
Gottfried K. Wehner
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WEHNER, GOTTFRIED, K.
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Individual
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Priority to AT89900684T priority Critical patent/ATE92113T1/de
Publication of EP0352308A1 publication Critical patent/EP0352308A1/en
Publication of EP0352308A4 publication Critical patent/EP0352308A4/en
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34—Sputtering
    • C23C14/3407—Cathode assembly for sputtering apparatus, e.g. Target
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34—Sputtering
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34—Sputtering
    • C23C14/3407—Cathode assembly for sputtering apparatus, e.g. Target
    • C23C14/3414—Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/01—Manufacture or treatment
    • H10N60/0268—Manufacture or treatment of devices comprising copper oxide
    • H10N60/0296—Processes for depositing or forming copper oxide superconductor layers
    • H10N60/0408—Processes for depositing or forming copper oxide superconductor layers by sputtering
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/01—Manufacture or treatment
    • H10N60/0268—Manufacture or treatment of devices comprising copper oxide
    • H10N60/0661—Processes performed after copper oxide formation, e.g. patterning

Definitions

  • the present invention pertains to sputtering by ion bombardment, deposition of multicomponent films, such as alloy or compound films consisting of two or more elements from the periodic table, and the substrate-target geometry in sputter deposition of a coating. More particularly, the present invention concerns a method for sputter deposition of films or coatings over large areas or at widely different substrate locations relative to the target where the coating is of exactly the same solid component composition as the target from where the material is being sputtered.
  • a flat planar alloy target contains only two metals, one can always find an ejection angle in which the composition is the same as in the target. But this is not usually the case when more than two elements are involved because each species has its own angular distribution and there exists no ejection angle in which all three would come together to form a film with exactly the composition as that of the target. Furthermore, to be restricted in substrate location relative to the target is highly impractical. Another complication with a planar target is the fact that the angular distributions of different species change with the bombarding ion energy.
  • the present invention which is set out in terms of independent method claim 1, and independent apparatus claim 15, overcomes the disadvantages of the prior art by not sputtering from a flat, but from at least one spherical or partially spherical target positioned in a uniform plasma of a triode or diode gas- or vapor-discharge or in a plasma which is created with radio frequency- or microwave-excitation.
  • a triode or diode gas- or vapor-discharge or in a plasma which is created with radio frequency- or microwave-excitation.
  • the general purpose of the present invention is the use of a spherical target where the conservation of mass law, together with the spherical symmetry of the target, guarantees that the composition of solids in the deposit is the same as in the target, regardless of where the substrate (within limits) is located. Even if such additional effects, such as evaporation or resputtering from the substrate, or poor sticking of a component becomes involved, the conservation of matter in a spherical-closed system requires that the composition remains unchanged from that of the target, no matter with what ion energy it is sputtered. With a new target, it will require some short presputtering for establishing equilibrium conditions.
  • the surface composition at the target then adjusts automatically to become different from that of the bulk in order to achieve the material removal with unchanged composition. It will, of course, be necessary to keep the target temperature below the value where constituents begin to move in the bulk and diffuse to the surface for replenishing the species which is most easily sputtered from there.
  • the present invention becomes less useful in a pressure regime where the mean free path of sputtered atoms becomes very short compared to the travel distance between target and substrate.
  • the collisions between sputtered atoms and gas or vapor atoms then make the ejection direction from the target immaterial.
  • many considerations exist for operating in the low gas pressure regime (0.132 Pa (10 ⁇ 3 Torr) with mean free paths of the sputtered atoms of several centimeters or larger) such as for retaining the high kinetic energy of sputtered atoms, or preventing the back diffusion of sputtered atoms to the target which lowers the deposition rate, or providing better adherence of those coatings.
  • Sputtering from a sphere at low gas pressure instead of from a flat target creates another very significant difference, namely with respect to the energies of the impinging atoms because they come not only from normal but as well from obliquely ejected atoms which are known to have higher ejection energies. This improves not only film adherence, compound formation, nucleation, and surface movements of atoms which in turn are beneficial for epitaxy at low substrate temperature.
  • Magnetron sputtering from prior art flat targets such as in FIG. 1, was invented not only for increasing the deposition rate, but for preventing the target-released electrons from bombarding and heating the substrate. At the spherical target or targets, these electrons are distributed over the whole surrounding volume which eliminates the need for magnetic fields for deflecting these electrons.
  • the spherical target will even solve problems which arise when a single element target is sputtered in an electronegative gas plasma for producing two component coatings such as metal oxides.
  • the bombarding positive oxygen ions are on impact partly converted into negative ions which again form in the case of a flat target a beam normal to the target surface, which is undesirable because they cause resputtering of material from the substrate.
  • those ions are however accelerated in radial directions and are therefore much diluted.
  • the present invention is particularly useful for the recently discovered ceramic high Tc superconductor materials.
  • FIG. 2 illustrates an electrically conducting target sphere held in position and connected to the negative pole of the DC-, or in the case of insulator coatings on a metal sphere, to an RF-sputter power supply.
  • the allowed substrate positions are limited to those not in line of sight with the sphere area where the connection is made.
  • the connecting lead to the sphere needs, of course, to be insulated from the plasma so that it would not be subject to sputtering.
  • the sphere can be made of the material to be sputtered or can be a metal sphere which is coated with a sufficiently thick layer of the material to be sputtered.
  • the distance between sphere and substrate and the sphere size have no influence on the composition, but both affect the deposition rate.
  • the relationship of the target sphere to the substrate must be such that sputtered atoms reach the substrate over the ejection angle range from -90° through 0 to +90°.
  • the only portion of a sphere that is required is that which provides such an ejection angle range over all parts of the substrate. If one tries to achieve high uniformity of the deposition rate over a flat surface, one should use a small target sphere and a large substrate distance like shown in FIG. 3, but then the deposition rate will become very small. If one uses the case of FIG. 2 with the substrate closer to a large target sphere, it may not only become difficult to fill the space between substrate and target with a dense uniform plasma, but the deposition rate on a flat target becomes more non-uniform unless one uses mechanical motions.
  • Sputtering of insulators can only be accomplished with RF power applied to a metal sphere which has the insulating material to be sputtered affixed to the outer surface of the sphere.
  • compositions of the deposits sputtered from spherical targets are maintained independent of substrate positions (within the limits as discussed), and independent of the distance between target and substrate, makes it possible to use more than one plasma-immersed spherical target, in particular in the case that the substrate-target distances are much larger than the target spheres.
  • three such spherical targets are arranged in a triangular configuration pointing towards a substrate located in a direction normal to the center of the triangle.
  • Spherical targets can also be arranged in a row for creating a "line source” of sputtered material, such as is usually used with "race track” magnetron sputtering sources for coating large glass panels which are transported continuously across the line source sputtering target.
  • the targets can be arranged in a circle, and a wire or rod to be sputter coated is drawn continuously through the center of the circle.
  • many spherical targets can be positioned in a triangular matrix fashion, or even in a three dimensional configuration, for achieving high deposition rate and high uniformity in thickness over large flat areas.
  • the immediate impact of the present invention is in the film deposition of the Y1Ba2Cu3O 7-x (referred to as 123) ceramic superconductors. These materials are pressed from powders which are mixed in the proper proportions and sintered, and annealed in oxygen at high temperature. Thin films of these materials are usually synthesized by vacuum evaporation or sputtering from two or three sources containing Y, Ba and Cu metals or their compounds. To achieve exactly the 123 composition of the metals in the deposits is not a simple task because it requires flux monitoring for each separate source and the location where one obtains exactly the 123 composition is very limited.
  • Sputtering from a single superconducting 123 target would be much simpler, but has so far not been very successful, at least not for producing 123 films over larger areas in the prior art.
  • the desired 123 composition in the deposit can be improved by changing the target composition accordingly.
  • the graph of FIG. 4 illustrates the results.
  • the present invention was experimentally proven in a mercury triode plasma with the electrons supplied from a cathode spot ignited on a Hg pool.
  • the reason for this plasma was the fact that this equipment was in place and operational, and that the inventor has a long experience in this equipment. The same results will no doubt be obtained in a noble gas triode discharge.
  • the specifics of one example (with the results shown in FIG. 4) of the present invention are as follows:
  • the target hemisphere had 4mm radius.
  • the substrate was a 5x6x1mm SrTiO3 crystal mounted about 4cm away from the target.
  • the main discharge current between cathode #22 and anode #30 was 4 amp with a voltage drop between anode and cathode of 25 volt.
  • the lower part of the Pyrex tube was immersed in water which was chilled to 11°C which sets the vapor pressure of Hg at about 0.066 Pa (5x10 ⁇ 4 Torr).
  • the tube was pumped with a 12L/sec Hg diffusion pump.
  • the target voltage was 300 volt negative w.r.t.
  • the floating voltage in this low pressure, very non-thermal, plasma was minus 17 volt w.r.t. anode which of course helps to sputter-clean the insulating substrate before sputter deposition is started.
  • the thickness of the deposited film was 700 nm and this was obtained in about 11 hours of sputtering.
  • Fig. 4 shows that the whole resistance curve from 300°K to 92°K curves downward, which differs from most other published data.
  • the T (10% to 90%) is still rather high. Full superconductivity is reached at 76°K.
  • the sample is an insulator after deposition, and requires the usual oxygen annealing procedure for incorporating the right amount of oxygen. The procedure was: 650°C for 90 min, 750°C for 30 min, 850°C for 20 min and 920°C for 3.5 min with subsequent slow cooling in oxygen to room temperature.
  • These films always need such a high temperature heat treatment after deposition for accomplishing the O 7-x (x 1) composition and for converting the material to the orthorhombic structure.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Manufacturing & Machinery (AREA)
  • Physical Vapour Deposition (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Photoreceptors In Electrophotography (AREA)
EP89900684A 1988-01-21 1988-03-24 Method of sputtering Expired - Lifetime EP0352308B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT89900684T ATE92113T1 (de) 1988-01-21 1988-03-24 Verfahren fuer dampfniederschlag.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US14630088A 1988-01-21 1988-01-21
US146300 1988-01-21

Publications (3)

Publication Number Publication Date
EP0352308A1 EP0352308A1 (en) 1990-01-31
EP0352308A4 EP0352308A4 (en) 1990-06-27
EP0352308B1 true EP0352308B1 (en) 1993-07-28

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EP89900684A Expired - Lifetime EP0352308B1 (en) 1988-01-21 1988-03-24 Method of sputtering

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EP (1) EP0352308B1 (ko)
JP (1) JPH0776422B2 (ko)
KR (1) KR900700652A (ko)
AT (1) ATE92113T1 (ko)
AU (1) AU2826089A (ko)
DE (1) DE3882704T2 (ko)
WO (1) WO1989006709A1 (ko)

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Publication number Priority date Publication date Assignee Title
JP3852967B2 (ja) * 1995-07-14 2006-12-06 株式会社アルバック 低圧スパッタリング装置
CN105671509B (zh) * 2016-03-31 2018-06-29 成都西沃克真空科技有限公司 一种球面靶阴极机构及溅射镀膜装置

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3021271A (en) * 1959-04-27 1962-02-13 Gen Mills Inc Growth of solid layers on substrates which are kept under ion bombardment before and during deposition

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3988232A (en) * 1974-06-25 1976-10-26 Matsushita Electric Industrial Co., Ltd. Method of making crystal films

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3021271A (en) * 1959-04-27 1962-02-13 Gen Mills Inc Growth of solid layers on substrates which are kept under ion bombardment before and during deposition

Also Published As

Publication number Publication date
EP0352308A1 (en) 1990-01-31
AU2826089A (en) 1989-08-11
ATE92113T1 (de) 1993-08-15
JPH0776422B2 (ja) 1995-08-16
JPH02501754A (ja) 1990-06-14
DE3882704T2 (de) 1994-01-13
DE3882704D1 (de) 1993-09-02
KR900700652A (ko) 1990-08-16
EP0352308A4 (en) 1990-06-27
WO1989006709A1 (en) 1989-07-27

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